Calling "argtoextrasymbol" of a function containing "g5_" crashes

[mgerlach-phys]

The following code crashes on execution without further error message.

cf f, g;

l A = f( g(g5_(1)) );
l B = f( g5(1) );
l C = f( gi_(1) );

argtoextrasymbol f;

print +s; 
.end

In this example code only the case B crashes. i.e. no error occurs in A and C.

I already found a walkaround, though. Just replace g5_ by an other generic tensor.

ntensor g5;
index rho;

[...]

argument f;
    id g_(rho?,5_) = g5(rho);
endargument;

[...]

[tueda]

I confirmed that f(g5_(1)) leads to crashes. Here is a Valgrind dump:

Valgrind dump

==119862== Memcheck, a memory error detector
==119862== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==119862== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==119862== Command: ./vorm test.frm
==119862==
==119862== Warning: set address range perms: large range [0xfc45040, 0x2d91b540) (undefined)
==119862== Warning: set address range perms: large range [0x2d91c040, 0x4b5f2540) (undefined)
==119862== Warning: set address range perms: large range [0x59eac040, 0x9e675bc0) (undefined)
FORM 4.2.1 (Aug 28 2019, v4.2.1-5-g4057c65) 64-bits  Run: Mon Dec  9 18:10:29 2019
    CF f;
    L F = f(g5_(1));
    argtoextrasymbol f;
    .end
==119862== Invalid read of size 4
==119862==    at 0x4DB990: DimensionSubterm (reshuf.c:942)
==119862==    by 0x4DBA2E: DimensionTerm (reshuf.c:975)
==119862==    by 0x4DBA85: DimensionExpression (reshuf.c:1006)
==119862==    by 0x46764B: FindSubexpression (notation.c:1129)
==119862==    by 0x409265: execarg (argument.c:612)
==119862==    by 0x4C12FB: Generator (proces.c:3439)
==119862==    by 0x4C1FFA: Generator (proces.c:3824)
==119862==    by 0x4C2440: Generator (proces.c:3992)
==119862==    by 0x4C39BF: Processor (proces.c:405)
==119862==    by 0x43ACD9: DoExecute (execute.c:843)
==119862==    by 0x4540B2: ExecModule (module.c:274)
==119862==    by 0x4B9627: PreProcessor (pre.c:967)
==119862==  Address 0x779570b64 is not stack'd, malloc'd or (recently) free'd
==119862==
Program terminating at test.frm Line 3 -->
==119862== Invalid read of size 4
==119862==    at 0x50E22F: Crash (tools.c:3771)
==119862==    by 0x4F3C3D: Terminate (startup.c:1721)
==119862==    by 0x4F425F: onErrSig (startup.c:1489)
==119862==    by 0x5C4230F: ??? (in /home/linuxbrew/.linuxbrew/Cellar/glibc/2.23/lib/libc-2.23.so)
==119862==    by 0x4DB98F: DimensionSubterm (reshuf.c:942)
==119862==    by 0x4DBA2E: DimensionTerm (reshuf.c:975)
==119862==    by 0x4DBA85: DimensionExpression (reshuf.c:1006)
==119862==    by 0x46764B: FindSubexpression (notation.c:1129)
==119862==    by 0x409265: execarg (argument.c:612)
==119862==    by 0x4C12FB: Generator (proces.c:3439)
==119862==    by 0x4C1FFA: Generator (proces.c:3824)
==119862==    by 0x4C2440: Generator (proces.c:3992)
==119862==  Address 0x0 is not stack'd, malloc'd or (recently) free'd